Short-ish Haul, 34 Mark1

Here are some more pics of the old expansion tank. Earlier I thought the aluminum was so thin and porous that the coolant was weaping through but now I believe it was all slow leaks at the old brittle hoses and at the freeze/expansion plug.

Probably the most disturbing find was a lot of oily sludge settled at the bottom of the tank, there was also similar sludge in the overflow tank. It was thicker and heavier than oil and clean coolant was floating above it. At best case, this thing overheated at some point, lifted the head and pumped oil into the coolant system and while the head gasket was replaced, the coolant system was never adequately flushed out. At worst case, the head lifted and the head gasket was never replaced but the head sealed back up after cooling off, this seems far fetched but I don't have any records of the head gasket being replaced or sign of the head being removed.

I really need to check the oil pressure with a mechanical gauge, it does not overheat but it also does not carry good oil pressure, it carries about 45 psi at idle when cold and only about 20 psi when hot at idle and around 30 psi at cruise (1700-1800). It is pretty consistent at both upper and lower helm gauges. I changed the oil immediately after purchase and it has 15W40 in it now with less than 15 hours on it.

If the mechanical gauge proves the sending unit to be accurate, I'm looking at lifting the engine in the boat, dropping the pan and replacing the main and rod bearings. Hopefully I'll be able to nurse it through the rest of the season first.

I finished replacing the heat exchanger tank. It took a bit longer than expected but that is par for the course every time I tear something apart. I removed that thermostat housing outlet and cleaned it up off of the engine and replaced the hose connections on the coolant side but was really not happy with the alignment of that pipe, it rises as it comes aft and makes for an poor fit at the tank, the new tank also has a 1 3/4" connection while the pipe is 2". I ended up using a 1 1/2" to 2" adapter hose section (with a bit of stretching) sold for automotive use which fits both nipples snugly but doesn't have much overlap and room to install two hose clamps as I would prefer. This of course would not sink the boat as it is on the coolant side of the system but I'm just not thrilled with it. I'm planning to do away with the pipe and go with all hose between the tank and thermostat housing, preferably a radiator hose with the right sizes on each end that happens to be the right length.

One off topic observation: Many people looking at these old boats are concerned about the parts availability and degree of support for these old perkins. That is a fair concern and especially deserved for the manicooler equipped units but to date, I have have received parts quickly at reasonable prices. Ironically, a friend has a pair of big four stroke yamaha outboards on his boat which are far from obsolete and one of the most common powerplants in my area. I believe his boat has been in the shop twice this season and he is still waiting on a relay for a starter. I believe it has been 3 or 4 weeks now.

I am not sure about what is normal for underway oil pressure on your engine, but the value you mentioned is well within what my brother and I have observed for decades on our four Lehman 120s.

rgano said:

I am not sure about what is normal for underway oil pressure on your engine, but the value you mentioned is well within what my brother and I have observed for decades on our four Lehman 120s.

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Thanks for that, it seems to be on the low end of acceptable specifications from what I've read but as long as it stays consistent, I'll be ok with that. I've yet to run the thing at an even an easy cruise pace (1800) longer than two hours. On my fathers T6.354.4, we ran the thing pretty regularly at 2200 rpm for hours and never saw less than 60 psi. Honestly we just ran it the way the previous owner had, eventually I came to accept that 1900-2000 was nearly as fast and much quieter & cheaper. It only had oil pressure and temp at one station and we never had a reason to test mechanically but I have a skewed basis of comparison I guess. When I first brought home (before I changed the oil), I have no idea how old the oil was and I believe I saw 15 psi when I was docking it. It just dawned on me the other day that the temperature and low oil pressure alarm is not functioning on this thing and I need to hook that back up.

As pessimistic as I sound, I am actually slowly growing in confidence with this thing and planning to start venturing further from home. The last thing I want to do is expose my wife and 3 kids to a break down. Now that I have what I consider to be an adequate anchor, I'm also less leery of putting this thing through it's paces.

Came down to the boar to knock out a couple projects with my 5 year old helper while my girls swam at the pool. Fist peoject was a breeze, topping off the hynautic ateering reservoir. Next planned chore was installing an ACR and checking my alternator output. It didn't seem to be putting out acording to the guages at the helm. Went to grab a cold beer from the fridge and had a warm and smelly surprise. Sometime in the last few days, the inverter died including the pass through function so my fridge was getting no power and died. I had planned to a standalone battery charger but had bot gotten around. This is a major flaw of the inverter/charger combo in nbmy opinion but I do like the convenience of pass through power. I have orgered a new unit, a little bigger and this time a pure sine unit. I bench tested my alternator and it isn't doing squat. I believe it will actually take the same unit as in my bow rider so I can try that out to rule out a wiring issue.

Gdavid said:

If the mechanical gauge proves the sending unit to be accurate, I'm looking at lifting the engine in the boat, dropping the pan and replacing the main and rod bearings. Hopefully I'll be able to nurse it through the rest of the season first.

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I wouldn't get out too far on this. Old electrical gauges are not to be trusted on absolute values in my experience.

Are there other possible sources of the sludge? I'm no expert, but maybe it's just a lot of years without regular or thorough cooling system flushes?

Thanks for sharing BTW. You'll have a good boat when you're done, as I'm sure you know. It's nice to see care being lavished on these older classics.

You know, I was toying with replacing the alternator with a higher output balmar and while having 70A output would be nice (I would have to change from a single v-belt to a dual or a serpentine belt if I wanted any more output than 100A), the stock Delco 65A alternator for $165 serves us fine. At our cruise of 1650, the output is around 45A so after a couple of hours of running, the batteries are charged (we only have a 270AH bank and that is the bare minimum with which we can get by). The alternator does get kind of hot, which I know will shorten it's life ,but for that little bit of $$ it costs, we just keep a spare onboard.
Oh, one of the best things I've added was an el-cheapo E-bay SOC monitor. $35 with a 300A shunt and we can now keep track of the battery usage while at anchor and the output of the alternator while underway.

boomerang said:

Oh, one of the best things I've added was an el-cheapo E-bay SOC monitor. $35 with a 300A shunt and we can now keep track of the battery usage while at anchor and the output of the alternator while underway.

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Agreed. Everyone should have one.

I am going to have to lookup that ebay SOC meter. I would like to have one but I wasn't about to spring for a balmar.

I swapped out my alternator tonight, I was surpeised that it had the same alternator as my 3.0 mecruiser. Maybe not what belongs there but it was a direct replacement for what I had before. When I was went to attach the wire that was in the "earth" position, I got a spark and then measured 6 V between that wire and the engine block, something is screwy. I left it disconnected and taped up for now. I did not start up to check whether it is charging as it was a bit late at my marina and alot of people are around enjoying the beautiful weather.

I wanted a standalone charger anyway so I think I will pick one up tonorrow from west marine and have a bit of redundancy after I get my new inverter/charger which is on the way from defender. I fully expect a christmas card from Defender this season.

I have a Balmar SG300 on my sailboat. Recently I put a Victron bluetooth shunt on my trawler, and it's great. I like the mobile app. Very simple install and it was something like $125.

boomerang said:

You know, I was toying with replacing the alternator with a higher output balmar and while having 70A output would be nice (I would have to change from a single v-belt to a dual or a serpentine belt if I wanted any more output than 100A), the stock Delco 65A alternator for $165 serves us fine. At our cruise of 1650, the output is around 45A so after a couple of hours of running, the batteries are charged (we only have a 270AH bank and that is the bare minimum with which we can get by). The alternator does get kind of hot, which I know will shorten it's life ,but for that little bit of $$ it costs, we just keep a spare onboard.
Oh, one of the best things I've added was an el-cheapo E-bay SOC monitor. $35 with a 300A shunt and we can now keep track of the battery usage while at anchor and the output of the alternator while underway.

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An alternator upgrade down the line is definitely a consideration but I have more pressing needs for now. Honestly, with a fully electic galley, I don't see ever going to long without running the generator. I think I would like to pursue a engine driven cooling compressor for refrigeration first. That would be a great solution to my largest energy requirement, along with some solar panels.

The boat is somewhat back together after my inverter fail. Not having a backup means of charging the batteries while waiting for my new charger/inverter unit to arrive bothered me so I rigged up this temporary setup to be able to connect a trickle charger/maintainer to my combined house/starter set. It is woefully undersized but the boat is just sitting at the dock with everything off but the bilge pumps. My 4 group 31 batteries sit on opposite sides of the boat and the only place they all connected before was on the inverter's posts via four sets of 2 gauge wiring, all equal in length. Without the inverter in place and without any terminal posts to tie them together, I rigged up this setup out of expanded PVC board.

When I came down to install my temporary battery maintainer, I also wanted to check the output of the alternator I had just replaced. The good news is that it put out power but something was still wrong, the case was hot and while I did not notice until after the engine was running, it had only run for about 30 seconds and I don't see how it could have heated up so fast. I believe the field wire had current running to it all night, after installing the unit. I need to dig into the dash and trace my ignition switch to figure out where it is pulling power from and which color line is going to the field wire. There has been all kinds of "customization" to the engine's wiring harness over the years and I have some clean up to do. I just disconnected everything and taped up the ends of the wires for now, my 5 year old helper was out of patience and rushing through wiring troubleshooting is not a good idea.

Please tell me your battery charger isn't set on 6 volts.....

Solly said:

Please tell me your battery charger isn't set on 6 volts.....

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I didn't think so but it sure looks like it in the picture

Solly said:

Please tell me your battery charger isn't set on 6 volts.....

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Solly, you were right, it was on 6V, I don't think it did any harm to the battery bank but couldn't bee good for the $20 charger. I just unplugged it for tonight, hopefully my new charger/inverter will show up tomorrow.

I really appreciate you noticing it, the charger was hot and not a safe situation.

+1 for the home team !! Us classic Mainship guys gotta stick together !

Seriously, just glad to pay one back to somebody on here ! I've learned sooooo much from others.

I got my electric al system back together. New Xantrex Freedom XC 2000, seems like an upgrade so far, it is pure sine versus my old modified sine wave unit. It also has far more features and settings i don't know if it will be as robust, the old promariner withstood alot of abuse before I bought the boat and I can't fault it for its untimely demise. I also got my alternator functioning, there is still a mess of custom wiring on the engine loom that I don't care for or fully understand.

I do like that the new inverter has settings to charge lithium phosphate batteries, if I keep the boat very long, I believe I will go this route. I still plan to add a standalone charger but will just carrry an automotive portable unit as a backup.

I have been losing transmission fluid, I use 30 weight engine oil as that is what appeared to be in it at purchase. The leak was getting worse and turned out to be the output flange nut completely lose. Just like the pinion bearing on a rear differential in a car, the nut tension is critical for keeping the bearing from running too tight to too loose and beating itself to death. I don't think it was run like this for long and I have rarely run the thing up to higher loads and even then for very short periods as I was checking out the cooling system but I will probably replace bearing in the off season. For now, I cleaned and reassembled the hub with RTV to seal the splines and thread locker on the nut. It is running smoother and with the hub centered the seal has a chance to do it's job. I have a new seal on the way but it is unlikely to arrive in time for me to install it prior to a trip planned next weekend.

We have been getting a fair amount of use of the boat and overall it has been running well. Since fixing the loose transmission output flange, the transmission has been retaining it's fluid, the engine oil level is stable (it was never losing oil but the SAE30 fluid leaking out of the transmission made me suspect some oil was coming from the engine), it has small leaks from the valve cover and probably a bit from the oil pan gasket but negligible amounts, I've added about 1 quart of oil all summer.

I do need to clean up and reseal my perko sea strainer, the gasket on top developed a leak and allowed air to be sucked in, starving my raw water pump and nearly overheating the engine. I made a gasket for the top whch solved the immediate problem but the whole thing needs to be disassembled, cleaned up and reassembled with the proper gaskets and a new plastic cylinder. I should have done earlier because the whole thing is green and ugly. I finally ordered the gaskets and cylinder.

Our longest trip of the season went pretty smoothly, only 4 hours away to Cambridge but still a milestone is gaining confidence in the drive train.

My oil pressure stays higher when I can keep the coolant temps at 175 or less, I'm going to switch to 20W-50 on my next oil change and also work on getting my raw water hose transitions a little smoother (slightly kinked at some molded 90's) in hopes of being able to run at or above 2k rpm and below 180 degrees coolant temp. I think soaking my exhaust manifold and intercooler with barnacle buster is in order as well.

I've been getting out to fish a little more often, with mixed results, hopefully the fall will provide some decent rock fishing, it can be hit or miss.

Gdavid said:

We have been getting a fair amount of use of the boat and overall it has been running well. Since fixing the loose transmission output flange, the transmission has been retaining it's fluid, the engine oil level is stable (it was never losing oil but the SAE30 fluid leaking out of the transmission made me suspect some oil was coming from the engine), it has small leaks from the valve cover and probably a bit from the oil pan gasket but negligible amounts, I've added about 1 quart of oil all summer.

I do need to clean up and reseal my perko sea strainer, the gasket on top developed a leak and allowed air to be sucked in, starving my raw water pump and nearly overheating the engine. I made a gasket for the top whch solved the immediate problem but the whole thing needs to be disassembled, cleaned up and reassembled with the proper gaskets and a new plastic cylinder. I should have done earlier because the whole thing is green and ugly. I finally ordered the gaskets and cylinder.

Our longest trip of the season went pretty smoothly, only 4 hours away to Cambridge but still a milestone is gaining confidence in the drive train.

My oil pressure stays higher when I can keep the coolant temps at 175 or less, I'm going to switch to 20W-50 on my next oil change and also work on getting my raw water hose transitions a little smoother (slightly kinked at some molded 90's) in hopes of being able to run at or above 2k rpm and below 180 degrees coolant temp. I think soaking my exhaust manifold and intercooler with barnacle buster is in order as well.

I've been getting out to fish a little more often, with mixed results, hopefully the fall will provide some decent rock fishing, it can be hit or miss.

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That's the same scenario we followed when we first got ours...the first few months of owning it, we stayed close to home and ended up replacing the starter that went bad but cranked one last time to get us home, and an engine water circulating pump that started leaking. The next year, in addition to the major boat rebuild work, was mostly electrical upgrading. I also replaced the engine seawater strainer but with the same ,less expensive though not as tough as a Perko, Raritan plastic unit that the boat originally had installed. We still cruised within a 3-4 hour comfort zone.
After that ,a turbo ,riser & exhaust manifold replacement really boosted our confidence and we took off for a week-long cruise. Everything performed flawlessly, with the exception of a couple of pretty substantial oil leaks appearing in our normally clean bilge. I figured out it happened after running above 1850 RPM but didn't have an idea why they appeared until talking with others on this forum that had similar issues after using synthetic oil. Coincidence or not, I had used a synthetic blend in my last change. J Leonard from here made me aware of a big culprit & I was able to reseal the starboard forward motor mount bolts and that stopped most of the leaking at the time. It seemed that ever since the oil change with synthetic, small leaks were appearing and our bilge was never 100% clean.
If we EVER get the boat back in one piece this year, with the engine gone through and the clutch rebuilt, in addition to some other substantial work we did while hauled out, our confidence level will be through the roof & we'll be comfortable going anywhere (as long as it's inland waters...a Mainship 34 isn't an ocean-loving craft) for as long as we want!
So, you're doing kind of like us. Take your time & get to know your boat and after a while, you'll know exactly what to expect from it. Just don't use synthetic oil!

Gdavid said:

in hopes of being able to run at or above 2k rpm

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Just bought a Mainship 34 MK I with the Perkins 6.354 160 hp. Love the boat. Have enjoyed following your thread. Also own a motorsailer with a 6.534 with 6000 hrs, 3000 by me. Still going strong, no issues. There are several schools of thought about best speed (rpms) to run the 6.354s. Some would say run them hard, last long time. Others including me would say back off a couple hundred rpms. Burn less fuel, use less oil, perhaps run a little cooler especially exhaust temperature, overall less stress. My experience so far with the Mainship is that the 160 hp is not enough to get the boat to plane, so it make sense to me to run at lower rpms. For what it’s worth.

Couple more thoughts. Have used Rotella (not synthetic) in the 6.354s. Either straight 30 or 10w40 depending on air and water temperature. Know others that do the same. Looks amazingly clear when pull dip stick. Seldom add oil between oil changes.

With regard to seaworthiness of the Mark I, agree not an open ocean boat. But have seen a number of them in the Bahamas. Pick a calm day.

Jc180 said:

Just bought a Mainship 34 MK I with the Perkins 6.354 160 hp. Love the boat. Have enjoyed following your thread. Also own a motorsailer with a 6.534 with 6000 hrs, 3000 by me. Still going strong, no issues. There are several schools of thought about best speed (rpms) to run the 6.354s. Some would say run them hard, last long time. Others including me would say back off a couple hundred rpms. Burn less fuel, use less oil, perhaps run a little cooler especially exhaust temperature, overall less stress. My experience so far with the Mainship is that the 160 hp is not enough to get the boat to plane, so it make sense to me to run at lower rpms. For what it’s worth.

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I really have no plans to run it above 2k for prolonged times but I do want to ensure that it is capable of running at open throttle without running hot, that is what I consider the threshold for the cooling system to be operating properly. I don't plan to sell any time soon but know that any potential buyer would expect it to run at WOT without overheating.

On my first trip in my father's old MKIII, I foolishly stayed out in worsening conditions in a following sea, pretty consistent 3' with short intervals and the boat did respond well to more throttle and I ended up running at higher rpms for a prolonged time. Interestingly, just before I made my turn towards a tributary, I slowed down to 4-5 knots and the helm seems more responsive at this speed as well compared to 7-9 knots. My boat has a lower HP rating and running quicker for better response may never be an option but I want the engine ready for anything I throw at it. My boat sits a little lower in the stern to begin with and this may help. Most importantly, I've become a better judge of when to stay at the dock.

I got the perko sea strainer cleaned up and reassembled with new gaskets, new plastic cylinder and replaced the bronze/copper hardware with stainless for now. It is nice that it is rebuildable but honestly, it would have been more cost effective to replace it with a cheaper unit. There are too many points of failure on this design and the parts are expensive, I don't see any real advantage over most cheaper alternatives.

Regarding sustained hi-RPM cruising, I'm out of luck because when the aftercooler went bad on ours, I opted to remove & bypass it. I'll only run it above 1850 for short bursts since the speed gain is minimal plus I don't have an EGT gauge and that's something that needs to be watched with no cooler inline.

boomerang said:

Regarding sustained hi-RPM cruising, I'm out of luck because when the aftercooler went bad on ours, I opted to remove & bypass it. I'll only run it above 1850 for short bursts since the speed gain is minimal plus I don't have an EGT gauge and that's something that needs to be watched with no cooler inline.

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What prompted your replacement of the exhaust manifold? I really have no idea of the condition of mine. That and the aftercooler are the only remaning components of the cooling system I have not cleaned out or replaced. Since it is raw water cooled, I'm sure it should prior to failure but I'm not sure how I should judge that. My runabout has a 3.0 mercuiser with a combined intake and exhaust manifold, if that leaks the engine will ingest water immediately so I am just replacing it (even though I am going to sell it). On my perkins I can't tell if it is restricting flow or about to rust through. My exhaust is mostly under the waterline and I cannot see how much water I am circulating.

I have seen the price of the aftercooler and understand why you did away with it. Honestly, a naturally aspirated version of this engine would do everything I really need and reduce complexity. You don't get much more power from the turbo in this configuration. If I am going to contend with the maintaince of a turbo and raw water aftercooler, it should be on an engine with enough power to run 14knts sustained.

Gdavid said:

What prompted your replacement of the exhaust manifold? I really have no idea of the condition of mine. That and the aftercooler are the only remaning components of the cooling system I have not cleaned out or replaced. Since it is raw water cooled, I'm sure it should prior to failure but I'm not sure how I should judge that. My runabout has a 3.0 mercuiser with a combined intake and exhaust manifold, if that leaks the engine will ingest water immediately so I am just replacing it (even though I am going to sell it). On my perkins I can't tell if it is restricting flow or about to rust through. My exhaust is mostly under the waterline and I cannot see how much water I am circulating.

I have seen the price of the aftercooler and understand why you did away with it. Honestly, a naturally aspirated version of this engine would do everything I really need and reduce complexity. You don't get much more power from the turbo in this configuration. If I am going to contend with the maintaince of a turbo and raw water aftercooler, it should be on an engine with enough power to run 14knts sustained.

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You answered the question of what prompted the replacement of our exhaust manifold in the very next sentence. I didn't know the condition of it or it's history. I might have been replaced in the past but I kind of doubted it because the boat lived most of it's life in fresh to brackish waters. It was showing no signs of deterioration externally but I wasn't wasn't willing to gamble what could be a catastrophe just to try to squeeze a couple of more years out of it. It's like the clutch that I just had rebuilt. It was performing fine but I wanted to be sure it was going to continue to perform fine. Basically it's gotten to the point where a lot of the work we're doing is preventative maintenance.
You're spot on with the reason I didn't replace the aftercooler. If it was able to bump the horsepower beyond 200 , I might've replaced it. But even with a functioning cooler ,160 HP isn't enough to make any difference, other than increase the wake size.

boomerang said:

You answered the question of what prompted the replacement of our exhaust manifold in the very next sentence. I didn't know the condition of it or it's history. I might have been replaced in the past but I kind of doubted it because the boat lived most of it's life in fresh to brackish waters. It was showing no signs of deterioration externally but I wasn't wasn't willing to gamble what could be a catastrophe just to try to squeeze a couple of more years out of it. It's like the clutch that I just had rebuilt. It was performing fine but I wanted to be sure it was going to continue to perform fine. Basically it's gotten to the point where a lot of the work we're doing is preventative maintenance.
You're spot on with the reason I didn't replace the aftercooler. If it was able to bump the horsepower beyond 200 , I might've replaced it. But even with a functioning cooler ,160 HP isn't enough to make any difference, other than increase the wake size.

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Makes sense, kind of what I figured but if there was some trick that someone had figured out like "remove flange A and feel the wall thickness" I would have been thrilled. I have no idea if mine is original or not and will plan on replacing it in the off season. I will disassemble the after cooler, rebuild and pressure test it.

People say to take them to a radiator shop for rebuild but I haven't seen a local radiator shop for 20 years, it is just like having a starter rebuilt, don't expect to find anyone still doing it locally.

I was a little hesitant to dump too much money into the supporting components of this engine until I had some more confidence that it isn't some time bomb and I should just save towards a repower but I'm pretty confident that the long block had enough life in it for me and it wouldn't be to bad to rebuild if need be. I am grateful to hear about avoiding synthetic oil for these, i have heard it in general about the seals in old engines being suceptable to damage but am glad for the reminder prior to making that mistake.

If a re-buildable starter or coolant pump for our backwards engines pops up on ebay, be forewarned that we may end up in a bidding war.

Thanks for comparing notes again.

Gdavid said:

If a re-buildable starter or coolant pump for our backwards engines pops up on ebay, be forewarned that we may end up in a bidding war.

Thanks for comparing notes again.

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Add injectors and fuel injection pump to that. Got a quote of $ 840 on my fuel injection pump service. Waiting on parts and a call.

More boat dollars....